Larry Summers has joined the growing list of people saying that Mitt Romney’s tax plan just does not work.

“It’s easy to say that ‘My plan is to eat ice cream sundaes and chocolate cake and hamburgers as much as I want, my plan is to lose 60 pounds, and my plan is to avoid painful exercise, and those are all my objectives and I’m committed to every one of them,'” the former top economic adviser to President Barack Obama said Thursday at the Center for American Progress, a left-leaning think tank. “You don’t know quite where you’re going to go if you’ve got all three of those objectives.”

“This is the first time that the challenger’s errors have, on my accounting, been measured in the trillions of dollars. This is daughter of voodoo economics,” the Harvard economist said.

Romney plans to slash taxes in a way that would largely benefit the rich and deprive the government of hundreds of billions of dollars in revenue, while also claiming that his tax plan will not increase the deficit. Romney has promised to additionally reduce the deficit and slash government spending by 18 to 26 percent.

Though Romney has promised to slash both marginal tax rates and corporate tax rates, among other changes, he has been vague about which tax loopholes he would close to make up for revenue lost as a result. Lately, Romney has obscured the idea that he would cut taxes for the rich.

“I’m not going to reduce the share of taxes paid by high-income people,” Romney said at the first presidential debate last week, a statement he echoed Tuesday on CNN.

Whether Romney’s tax plan adds up has become a subject of contentious debate. The Tax Policy Center concluded in a recent study that Romney’s tax plan is impossible without raising taxes on the middle class. But Princeton economics professor Harvey Rosen found that Romney’s tax plan is mathematically possible without raising taxes on the middle class, assuming that Americans’ incomes grow.